Darting silently in formation, the mysterious glowing orbs light up the night sky.

Some say these orange lights even weave in between each other with the precision of a synchronised flying team from some far corner of the universe.

Clusters of more than 100 have been spotted across Britain and even Holland, leaving onlookers with an eerie sense that, for all the mystifying beauty of the strange objects, they may have just witnessed an armada of invading UFOs. The most recent sighting was on Sunday when they were seen in two locations, Merseyside and Lincoln. Days earlier a similar phenomenon was spotted over Cambridgeshire, where one witness claims each was as big as a house.

The sightings have prompted defence officials to check their logs and sent UFO fans into orbits of excitement. Engineer Paul Slight, 54, took photos on his mobile phone of the strange objects hovering over Lincoln at 10.30pm while he was cycling home after a day out with friends.

'There were 26 of them at first, dodging and darting in between each other like they were playing a game,' he said.

'After that, seven more arrived and weaved through the crowd of lights like strange kinds of aircraft. After five minutes of moving around, they hung in the air for a second then shot off into the sky and disappeared.'

A spokesman for nearby RAF Cranwell said the base was closed at the weekend so the lights could not be attributed to its aircraft. Meanwhile, the Ministry of Defence is examining claims that the Merseyside lights were connected to an exercise involving HMS Daring, docked in Liverpool.

An ex-military source claimed the lights were dropped by jets to simulate the path of a missile in order to test the warship's radar systems.In Cambridgeshire, banker Scott Boswell, 37, said he saw more than 100 lights flying less than two miles above his home in Hinchingbrooke. The former soldier and experienced pilot said: 'I know they weren't aircraft – they were silent.

'And I was a soldier for a decade so I could immediately rule out flares or weather balloons. I really have no idea what they were.'

On the same night, May 27, at around 11.30pm guesthouse owner Auberon Hedgecoe, 40, of nearby Huntingdon, also saw the lights. 'There was no sound,' he said.'They were travelling 15 at a time and every six minutes more seemed to be coming over the horizon. They were not planes. They were not balloons.

Each one was the size of a building.' Last night it emerged a woman has contacted her local newspaper to claim that the lights over Lincoln were Chinese lanterns – mini hot air balloons – set off at her wedding reception.

'They looked amazing, hope you all enjoyed the spectacle,' she said.

Nick Pope, the former head of the MoD's UFO Project, supported the Chinese lantern theory.

'I'm not disparaging the whole UFO phenomenon, but I'd say 99 per cent of UFO reports involving orange lights in the sky these days are attributable to these lanterns.'